`Keitt' and `Tommy Atkins' mango (Mangifera indica L.) fruit were evaluated for selected ripening criteria at six ripening stages, from mature green to overripe. `Tommy Atkins' mangos developed more red and yellow pigmentation (CIE a* and b*) in peel and mesocarp tissues than `Keitt'. The outer mesocarp of `Keitt' remained firm longer than `Tommy Atkins', and the inner mesocarp was softer than the outer at each stage in both cultivars. Cell wall neutral sugars, particularly arabinosyl, rhamnosyl, and galactosyl residues, decreased with ripening in both cultivars. `Keitt' had more loosely associated, chelator-soluble pectin, accumulated more soluble polyuronides, and retained more total pectin at the ripe stage than `Tommy Atkins'. Both cultivars had similar polygalacturonase (EC 3.2.1.15) activity which increased with ripening. The amount and molecular weight of cell wall hemicellulose decreased with ripening in both cultivars. These data indicate that enzymatic and/or nonenzymatic processes, in addition to polygalacturonase activity, are involved in the extensive softening of mango fruit.

Treating Mexican grapefruit with gibberellic acid (GA3) before color break, significantly delayed peel color change and increased peel puncture resistance, but it did not reduce grapefruit susceptibility to Mexican fruit fly, Anastrepha ludens (Loew) attack under natural conditions. Despite GA3 treatments, larval infestation levels increased with higher fruit fly populations, which also increased as the season progressed. Late in the season, infestation levels were even higher in GA3-treated fruit compared with untreated fruit, possibly because treated fruit were in better condition at that stage. Egg clutch size was significantly greater in very unripe, hard, GA3-treated fruit at the beginning of the harvest season and in December, compared with control fruit. Under laboratory conditions, egg injection into different regions of the fruit suggested that A. ludens eggs are intoxicated by peel oil content in the flavedo region. However, A. ludens' long aculeus allows females to oviposit eggs deeper into the peel (i.e., albedo), avoiding toxic essential oils in the flavedo. This makes A. ludens a particularly difficult species to control compared with other citrus-infesting species such as Anastrepha suspensa (Loew), Anastrepha fraterculus (Wiedemann), and Ceratitis capitata (Wiedemann) (fly species with significantly shorter aculei), which can be effectively managed with GA3 sprays. We discuss our findings in light of their practical implications and with respect to the oviposition behavior of various fruit flies attacking citrus.

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